Process of absorbing oxids of nitrogen.



C. BOSCH & H. KELLER. PROCESS or ABSORBING oxrns oF NITROGEN.

APPLICATION FILED JUNE 22,1909.

C. BOSCH & H. KELLER. PROCESS OP ABSORBING OXIDS 0F NITROGEN.

\ APPLICATION FILED JUNE 22,1909. 1,029,528, Patented June 11, 1912.

2 SHEETS-SHEET 2y TED sTATEs PATENT oEEioE.

CARL BOSCH AND HANS. KELLER, `01E' LDWIGSHAFEN-ON-THE-RHINE, lGERMANY,

ASSIGNORS TO BADISQHE ANILIN @c SODA FABRIK, OF LUDWIGSHAFEN-ON-THE- lREINE,y GERMANY, A CORPORATION.

PROCESS OF ABSORBING OXISDS OF NITROGEN.

To all whom 'it may concern: Y

Be it known that we, CARL BoscH and HANS KELLER, ,doctors of philosophyand chemists, subjects of the Klng of Prussia, residing at Ludwigshafenon the Rhine, Germany, have invented new and useful Improvements inProcesses of Absorbing' Oxids of Nitrogen, of which the following is aspecication.

- suspension of a base, or of a basic substance,

is effected by introducing a suspension of an absorbent into the gasmixture in a state of tine division, for instance as a spray, or mist.The vresults obtained thereby` are very satisfactory, the gases beingbetter absoi'bed than they are according to the first- 1mentionedprocess, and the process accord ing to our invention being capable ofbeing worked continuously without interruption.

In spite of the large quantities of gases which have to be treated, theapparatus required for the purposes of this invention is comparativelysmall, 'and less power is required 'to keep the gases` in circulationthan is required for the first-named process. As bases which areparticularly suitable for use according to this invention, we mentionthe oxids, hydroxids, and carbonatos of the alkaline earth metals and ofmagnesiuni. Particularly good results are obtained when using lnillcoflime.

()f course the process of our invention can be used either for theabsorption of the whole quantity of oxids of nitrogen contained in thegases leaving the electric arc llame. or for absorbing the nitrogenouscompounds which reniain in the gases after they specincaaon'of LettersPatent. Patented Jun-e 11, 1912 Application led .Tune 22, 1909. SerialNo. 503,637.

have been partially treated for absorption, for instance after they havebeen treated with "water for the production of-nitric acid. The processof this invention can be carried out in very many different methodsWithout departing from the'nature of our invention. For instance, theabsorption can be carried out in towers, or in apparatus of any othersuitable shape, such for instance as in a number of tubes through whichthe gases pass in series, or if the tubes be sutliciently large they maybe arranged in parallel. If desired, other shaped vessels can beemployed. Then again, the suspension of the absorbing agent can beintroduced into th apparatus Vin any suitable manner. As instances ofmethods which can be used according to our invention, but without in anyway limiting ourselves to the methods which we quote here, we mentionthat the absorbing agent can be introduced through any suitable sprayingnozzle, and it can lbe forced into the apparatus, if desired, by meansof compressed air, or, instead of compressed air, the gases containingthe oxids of nitrogen can themselves be employed for assisting in theintroduction and spreading out intoa state of fine division of theabsorbing agent.

lnstead of using compressed air, or the nitrous gases themselves, othermethods can vbe employed, for Instance, the suspension can be made toenter the apparatus by means of its own weight, or it can be forced inby mechanical means. The method of causing the entering, or entered,suspension to assume a state of fine division can also be varied in anysuitable manner. For instance, suitable nozzles can be employed, eitherone, or, preferably, more, in each piece ot' apparatus. The nozzles mayallow only the absorbent suspension to enter, or vthey may be such thatat the same time ai-r, or other gas,

lenters and assists in spreading out the sus- '.lhe nozzles may remainstationi-A pension. ary, or they may have motion imparted to them. Ifdesired, the suspension can enter through the nozzle in the form ot' ajet and then be subsequently spread out, for instance by causing it toimpinge on a suitable surface, either stationary, or in motion, or inany other suitable manner. AThe gases, containing, for instance two percent. of nitric oxid, can be passed into the tower, or other' apparatus,either at the top, or at the bottom, or at any ot-her suitable point, orpoints, and at the same time the suspension, for instance, milk of limeof six degrees Baume, is passed into the apparatus in any suitablemanner, such for instance as hereinbefore described. In this manner anabsorption of from ninety-eight, to ninety-nine, per cent. of thenitric'oxid can easily be effected. n

The drawings accompanying this specification represent in verticalsection two forms of apparatus suitable for carrying out the process ofthis invention.

In Fig. 1 C, D represent two towers joined together at the top by thepipe E, the gases enter at the bottom of the tower C, through theopening F, and leave the lower end of the tower D, through the openingG. H H

representsuitable nozzles through which the milk of lime is sprayed intothe towers, there being several such nozzles in each tower, asrepresented in the drawing.` The milk of lime Hows down to the lower endof each tower and through an outlet into the tank B and is thence raisedby means of the pump A and again forced through the nozzles H H in theform of spray. This is repeated until the milk of lime has absorbedsuflicient of the oxids of nitrogen.

`In Fig. 2 the gases are made to pass in a Zg-zagmanner along passages LL which are formed in the tower C by means of partitions K K, arrangedafter the manner of baille plates. At the end of each such artition anozzle H is situated through W ich milk of lime is sprayed into thespace between the partition or the like. In this case the gases enter atthe lower end of the tower C and leave at the top, while the milk oflime after being used flows into the tank B and is raised again by thepump A and forced through the nozzles afresh.

A very suitable form of apparatus for use in carrying out the process ofour invention consists of a series of tubes or passages arranged in amanner somewhat similar to that shown in Fig. 2, in which the gases arecaused to pass through the series of tubes or passages in a zig-zagdirection, that is to say, along one passage and then back again in theopposite direction along the next passage, and so on, while at the endof each such tube or passage a nozzle for spraying in the milk of limeis situated. The tubes or passages canhbe placed side by side, and alsoone above the other so that they take up a minimum of space. In any casethe milk of lime can be sprayed into the tube .or passage, either in thedirection of motion of the gases or in the opposite direction, as shownin Fig. 2, or any other convenient means ot spraying can be followed.

Now what we claim is 1. The process of absorbing oxids ot' nitrogen frommixtures containing them, by introducing a suspension of 4an absorbentinto the gas mixture in a state of fine division.

2. The process of absorbing oxids of nitrogen from mixtures containingthem, by introducing milk of linie in a state ot' fine division into thegas mixture.

3. The process ofabsorbing oxids of nitrogen from mixtures containingthem, by spraying milk of lime into the gas mixture.

In testimony whereof we have hereunto set our hands in the presence oftwo sub scribing witnesses.

CARL BoscH. HANS KELLER.

Vitnesses ERNEST F. EHRHARDT, J. ALEC. LLOYD.

